Tank safety device



March 13, 1934. D. w. DAVISSON El AL 1,951,009

TANK SAFETY DEVICE Filed Aug. 31, 1931 55mm CC FIG. 5

24 SECTION A-A 5ECTION 5B FIG. 2

' ated and are in use.

Patented Mar. 13, 1934 TANK SAFETY nnvron Delos W. Davisson andFerdinand G. Welke, San

Francisco, Calif., assignors to Shell Development Company, SanFrancisco, Calm, a corporation of Delaware Application August 31, 1931,Serial No. 560,280

'1 Claims. (01.220-24) This invention relates to containers forinflammable liquids and is more specifically concerned with theprevention of explosion of tanks used for transporting gasoline in bulk.

It is well known that gasoline and similar fluids are ever a menace offire or explosion when in storage, and that they are even more dangerouswhen transported in bulk, as for instance, when the tanks containinggasoline are mounted upon wheels and moved from place to place.

In order to minimize the danger of fire and explosion, most gasolinetanks are equipped with safety devices; such safety devices being arequirement by law in many jurisdictions. Various types and forms ofsafety devices have been cre- Some tanks are fitted with fusible plugsin the dome covers of each tank, so that in the event of the tankbecoming heated, the plugs will melt, thus relieving the internalpressure that would have built up inside the tank with the consequentdanger of explosion. In practice these fusible plugs have not been foundeffective under all fire conditions, for instance, when there is a firedue to a leak in the bottom 01 a tank. The plug being situated in thetop oi the tank is not near the seat of confiagration, so

that the temperature of the tank may only be appreciably raised near theflames, and conseuently the fusible plug will not be melted. The heatingof the gasoline inside the tank will cause a considerable pressure to bebuilt up inside the tank. Often this pressure may be so great as tocause the tank to burst which may cause a great amount of damage.

Difierent types of vents have also been fitted to the tops of the tanks.Some of these vents have the disadvantage that if the tank is turnedupon its side as may happen in an accident, the pressure of the liquidwill cause the vent to jam in a closed position, thus making it uselessfor the purpose of relieving the internal pressure. Fire may then causethe tank to explode.

Some vents fitted to tanks are of small diameter so that sometimes whenthe tank is highly heated as by fire the ventscannot cope with the rapidincrease in pressure inside the tank due to vaporication of the contentsand as a result the tank may burst. y I ow we have foundthatibythe'use'o nicenstructicn, the above dicadvarn may be avoided.

, om the following detailed a tion threat to attempt... .-g

dome various features of our invention whl heat which reference isFigure I is a plan view of the dome cover.

Figure II is a view in elevation of the dome cover through A-A of FigureI.

Figure III is a view in elevation showing the -hinged end oi the domecover through (L-B of Figure I.

Figure IV is a view in elevation showing the fastener end of the domecover through B-B of Figure I.

Referring to Figures I and II, (1) represents a dome cover fitted to aseat (2) held in place by strongbacks (3) and clamping members (4) Theseat is therefore rigidly attached to the tank (5) only part of which isshown. A. gasket (6) is interposed between the seat and the tank to makea gastight joint. Another gasket ('7) is fitted to the dome cover forthe same purpose.

The dome cover is at one end mounted upon a hinge pin (8) about whichthe cover can turn. The ends oi the hinge pin are slidable traversely ingrooves (2%) in raised sections (9) oi the seat, as shown in Figure III.

The raised sections (9) are hollow on the inside, coiled springs (10)are interposed between the closed tops (ll) and the hinge pin (8) Thehinge pin is prevented from falling out by pins (12).

' 'The other end oi. the dome cover has a catch portion (13) whichco-operates with a latch (1i) attached to the seat.

The latch is mounted upon a hinge pin (15) attached to the ends of whichare link pieces (16) which are in turn fastened to a hinge pin (it) Theends of this latter pin (it) are slidable traversely in raised sectionsof the seat. (it) as at the anchored end of the dome.

By the use of the term slidable traversely we mean that the hinge pinsare movable in directions perpendicular to their longitudinal axes.

The springs (19) at the latch end oi the dome cover are more flexiblethan those at the hinged end. The hinge pin (1'?) is prevented fromfalling out by a long pin (20). The long pin also acts as a stop for thelatch when the dome cover is open.

In the middle oi the dome cover is a. one way air inlet valve (21)having air inlet holes (22) and a; ring valve piece (23).

For the filling operationthe dome cover is used in the ordinaryway byreleasing the .(ldl the cover bach'upon its in the closed position thedome cover is her airtight upon the (ii) due to the press ire of theupon the hinge pins (d) and (lii.

"fire springs are at sueh strength that an inter oi about noundsuersuuare s inch will cause the cover to further compress the springs, sothat the hinge pins will move upward in the grooves (24) allowing thecover to raise from its seat and release the pressure inside the tank.

It will be readily understood that by changing the springs we may causethe cover to open at any desired pressure below the bursting point ofthe tank to which the cover is fitted.

A slight internal pressure may exist in a tank fitted with our domecover. An internal pressure will exist in a tank so fitted when thegasoline in the tank is raised to a higher temperature than thetemperature of the gasoline when it was loaded. Such a condition willexist when the tank is used in a hot climate. The existence of thisinternal pressure reduces loss of light fractions of the gasoline byevaporation, as well as materially aiding in the discharge of gasolinefrom the tank.

Among the other advantages resulting from the use of our dome cover maybe mentioned the following:

As the dome cover is fitted with an air inlet valve a vacuum cannotexist in the tank and thus retard the emptying of the tank. The domecover being held in place by springs prevents a high pressure beingbuilt up within the tank so that the danger of explosion is avoided.Even if the tank is turned upon its side the dome cover will stillprevent explosion of the tank, as the cover will raise to release excessinternal pressure, but

will close when this pressure has been released, thus reducing theamount of liquid lost.

A further advantage of our dome cover when fitted to tanks mounted uponmotor truck chassis or upon motor truck trailers is ,that when going uphill or over an uneven road with a full tank of gasoline, spilling ofthe gasoline cannot result owing to the normally airtight construction.

While inthe above specification we have described our dome cover asapplied to tanks used for the transportation of gasoline it should beunderstood that we may apply our dome cover to gasoline storage tanks orto tanks used for the storage or transportation of other inflammableliquids.

We claim as our invention:

1. A safety dome cover assembly comprising a dome cover, a seat belowsaid dome cover, a hinge pin connecting the dome cover to one end ofsaid seat, a latch attached to the other end of the seat, a hinge pinconnecting said latch to the seat and springs above the hinge pins, saidhinge pins being slidably mounted in the seat.

2. A tank truck dome cover assembly comprising: a dome cover, a seatbelow said dome cover,

a hinge pin slidably connecting the dome cover to one end of said seat,springs under compression in the seat above said hinge pin, a secondhinge pin slidably connecting a latch to the opposite end of said seat,springs under compression in the seat above said second hinge pin, andmeans whereby the latch cooperates with the dome cover to hold said domecover in yieldable contact with said seat.

3. A tank truck dome cover assembly comprising a dome cover, a seatbelow said dome cover, a hinge pin slidably connecting the dome cover toone end of said seat, springs under compression above said hinge pin inhollow sections of said seat, a second hinge pin, slidably connecting alatch to the opposite end of said seat springs under compression abovesaid second hinge pin in hollow sections of said seat and means wherebythe latch cooperates with the dome cover to hold said dome cover inyieldable contact with said seat, substantially as described.

4. A safety dome cover assembly comprising a dome cover, a seat belowsaid dome cover, a latch, a link attached to said latch, a hinge pinconnecting said link to said seat, said hinge pin being slidable in saidseat at right angles to the longitudinal axis of said hinge pin, andsprings under compression above said hinge pin whereby said dome coveris held in yieldable contact with said seat.

5. A safety dome cover assembly comprising a dome cover, a seat belowsaid dome cover, a latch, links attached to said latch, a hinge pinconnecting said links to said seat, said hinge pin being slidable insaid seat at right angles to the longitudinal axis of said hinge pin andsprings under compression above said hinge pin whereby said dome coveris held in yieldable contact with said seat.

6. A safety dome cover assembly comprising a dome cover, a seat belowsaid dome cover, a hinge pin connecting one end of said dome cover tosaid seat, said hinge pin being slidable in said seat at right angles tothe longitudinal axis of said hinge pin and springs above said hinge pinin hollow sections of said seat.

7. A dome cover assembly comprising a dome,

a seat below said dome cover, a hinge pin connecting the seat to thedome cover, said hinge pin being slidable in said seat at right anglesto the longitudinal axis of said hinge pin, springs in said seatcontacting said hinge pin whereby said dome cover is held in yieldablecontact with said seat.

D. W. DAVISSON.

FERDINAND G. WELKE.

